It is frequently desirable to form a non-slip or skid-resistant surface on the surface of thermoformed objects such as truck bed liners. Typically, truck bed liners are thermoformed from blanks of extruded plastic material. The plastic is extruded into a continuous sheet which is wider than necessary for the mold of a thermoforming machine. Typically a pattern is formed on one side of the sheet by embossing the top surface of the sheet with a roller having a pattern as the sheet exits the extruder. The pattern is typically formed to have a texture and appearance of leather. Although the roller forms indentations in the surface of the sheet, the surface is sufficiently smooth that cargo and the like can slide on the surface of the truck bed liner when a vehicle turns, stops or accelerates.
Accordingly, various methods have been employed by the manufacturers of liners to prevent movement of cargo. It is known as disclosed in U.S. Pat. No. 5,265,993 to Wayne to mount cross members or dividers above the floor of the liner to form a grid to hold cargo from movement.
It is also known as disclosed in U.S. Pat. No. 5,549,428 to Yeatts to form devices which have ribs which lock in the longitudinal grooves of the floor. The top surface of the device is formed of material which produces greater friction than the surface of the liner and thereby reduces movement of the cargo.
Finally, it is known to cover the top surface of the liner with a skid-resistant coating, such as disclosed in U.S. Pat. No. 4,693,507. However, the coating prevents the recycling of scrap liner material, thereby adding greatly to the cost of the liner.
Accordingly it is an object of the invention to produce a slip or skid-resistant surface for a liner which is economically produced.